I'm looking for a Windows calculator that has a dual dec/hex display.
That is, assuming I'm adding in Hex mode, I want to have another line showing me the decimal value of my current Hex calculation.
Something like:
Display1: 0x1000
Display2: 4096



I have been using PCalc from analogX since I can remember. It can be downloaded for free from AnalogX website. 


If you’re using Windows 7 then it’s got an inbuilt calc to do this without needing to download thirdparty calcs. 

